Abstract/Description

Small ruminants in general and sheep in particular are important investments in the highlands of
Ethiopia. Genetic and environmental improvements offer an opportunity to increase production
from existing animal resources. Development of effective genetic evaluation and improvement
programs requires knowledge of the genetic parameters (genetic variance of each trait and covariance
among traits) for economically important production traits. Direct heritability estimates
for birth weight of Afar sheep (0.13 to 0.38) and BHS (0.20 to 0.58) using univariate analysis; for
Horro sheep (0.18 - 0.32) and Menz sheep (0.46) by fitting a multi-trait individual animal model.
The weaning weight direct heritability estimates for sheep in Ethiopia, Afar sheep (0.11 - 0.37)
and BHS (0.00 - 0.29), Horro sheep (0.10 - 0.26) and Menz sheep (0.48). Fertility, litter size and
lamb survival are the components of the overall ewe reproduction traits. It appears that heritability
estimates of these traits are rather low and reflect the generally small genetic variance for
most reproductive traits. Moreover, litter size has a higher heritability (0.16 - 0.19) than the other
components traits like fertility (0.10) and survival rate (0.07 - 0.09) for Awassi sheep breed. Genetic
correlations among most pairs of traits were higher than the corresponding phenotypic correlations.
Live weights measured at successive ages were highly correlated, ranging from 0.61 to
0.98 for Menz sheep. Genetic correlations were also high between pre-weaning daily gain and
weaning weight for Afar and BHS sheep. Except for Blackhead Somali sheep breed which has high
genetic correlation between birth weight and weaning weight, Horro, Menz and Afar sheep have
high genetic correlation between post-weaning weight traits. This indicates that selection for one
trait improves the other trait in those sheep breeds. In order to develop alternative improvement
program for sheep breeds in Ethiopia, estimates of genetic parameters for economical growth and
reproduction traits should be done by designing experiments since the information on most sheep breed is nonexistence.